Final answer:
The difference between direct geothermal and a geothermal heat pump is the method of heat extraction; direct geothermal uses Earth's internal heat, while geothermal heat pumps use the near-surface constant temperature for a heat exchange system.
Step-by-step explanation:
The main difference between direct geothermal heating and a geothermal heat pump system is the method of heat extraction. Direct geothermal heating involves extracting thermal energy directly from the Earth's crust, utilizing hot water or steam that comes from underground reservoirs, and is often associated with tectonic plate boundaries. However, a geothermal heat pump (GHP), also known as a ground source heat pump, does not rely on geothermal energy as a source but instead uses the constant temperature of the Earth near the surface as a heat sink in summer or heat source in winter, by moving heat into or out of the building via a heat-exchange system.
A geothermal heat pump operates more efficiently because it leverages the smaller temperature difference between the ground and the indoor environment it is conditioning, as opposed to the much larger temperature differentials that air-source heat pumps have to manage. Installations for both systems are distinct; geothermal systems might require drilling deep wells for accessing steam or hot water, while GHP systems involve drilling to a shallower depth to install a looped piping system for the heat exchange. Therefore, the correct answer to the student's question, based on the extraction method, is B) The method of heat extraction.